I'll probably be drawn and quartered, but my vote for current LEAST popular Amiga is the A1000. As stock, it's a little TOO retro. (Kickstart on a floppy disk? OCS? 256KB RAM? OUCH!) As upgraded, it kind of loses it's novelty as the first Amiga. (It's the first Amiga, except I added a real Kickstart board, wedged in a hard drive and a sane amount of RAM, or even swapped the whole motherboard! But it's still somehow the first Amiga! ...errr...).
The 600 was (rightfully) the least popular on release. It was one of Commodore's worst decisions, and that is saying something, being from a company known for bad decisions. But, today, since ALL Amigas are so retro, The A600's cute shape and compact size make it kind of adorable. And the PCMCIA and memory slots now have easy to obtain accessories available, so that has helped it gain popularity, as well.
To me, the A500+ was just a revision of the A500. Sure, you got a 2.04 ROM with it, but you could buy a $20 kickstart switch, and pick up a cheap (or sometimes free) 1.3 ROM from your local C= dealer, and voila, instant compatibility obtained. Quite FAR from the least popular. (And if you had an A500, you probably bought that same kickstart switch and socketted a 2.04 on it, so you could use newer utilities, anyhow, so I really fail to see any real relevance in caring which ROM version shipped with any particular A500 revision.)
Back in the day, having the kickstart switcher, ECS Agnus, and PAL/NTSC switch were typically the telltale marks showing that someone actually USED that A500.
